A medieval Chinese scholar deduced climate change from buried bamboo
Around the 11th century, Shen Kuo found petrified bamboo underground in a region far too dry to grow it. He concluded that climates shift over vast stretches of time. Climatology still works in that spirit, reading ice cores, tree rings and centuries of thermometer records to understand how climate changes.
Climate is weather averaged over at least 30 years, while weather is the atmosphere's state over a short spell. The field sits within the atmospheric sciences and physical geography, borrowing from oceanography and biogeochemistry. Its word comes from the Greek klima, slope, a reference to the tilt of Earth's axis. Hippocrates' On Airs, Water and Places, written about 400 BCE, linked climate to health and to differences between peoples, planting the long-lived idea of climatic determinism.
Thermometers and barometers made systematic records possible, beginning in England in the early 1640s. Edmund Halley published a map of the trade winds in 1686, Benjamin Franklin charted the Gulf Stream to speed transatlantic mail, and Francis Galton coined the word anticyclone. In the early 20th century the discipline was largely descriptive, giving farmers statistics on normal weather and the odds of extremes, and assuming climate changed only very slowly. Climate change became a central research topic only from the 1970s.
Today climatologists combine observation with modelling. Evidence ranges from satellites and a worldwide thermometer network to ancient ice drawn from glaciers, though changing instruments mean old and new records cannot always be compared directly. Paleoclimatology reconstructs the deep past from ice cores and tree rings, and paleotempestology uses the same archives to estimate hurricane frequency over millennia. Recurring patterns such as the El Niño–Southern Oscillation and the North Atlantic oscillation help bridge short forecasts and long-term climate.
The physics is expressed as coupled, nonlinear differential equations that can only be solved approximately, by numerical methods inside global climate models. Every such model balances, or very nearly balances, incoming shortwave sunlight against outgoing infrared radiation. The simplest treat Earth as a single point; more elaborate ones add vertical layers, horizontal detail and interacting oceans, land and ice. They serve both to study how the system behaves and to project future climate.
Source: Climatology
